JPH0571331B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for easily manufacturing a press mold using a low melting point alloy.

(Conventional technology) Conventionally, in order to easily manufacture press molds, plaster and sand molds were sequentially transferred from the mother mold, and a low melting point alloy (mold material) such as zinc alloy (ZAS) was cast into the sand mold. Method (“Metal Press” November 1976 P16, 17)
was generally adopted, but according to this method,
There were problems in that there were many transfer steps, which lengthened the mold production period and increased the cost burden.

Therefore, we integrated the press equipment and melting equipment,
A dual-form method in which a punched molded object model (matrix) with a product thickness similar to that of a sheet metal model is immersed in a molten low-melting-point alloy in a melting tank and solidified to obtain a punch and die at the same time. (Tokuko Showa 48-
7576), or as a modification of the dual-form method, a non-perforated molded body model is used, the outer surface of the molded body model is brought into contact with a molten low melting point alloy, and an alloy different from the above-mentioned alloy is applied to the inner surface of the molded body model. Method of simultaneously obtaining punches and dies of dissimilar alloys by pouring and solidifying the metal (Special Publication No. 53-15969)
Publication No. 51-55733, etc.) was established,
It has already been put into practical use. According to these methods,
Since the punch and die can be obtained at the same time through the molded body model, the efficiency of mold manufacturing is greatly improved compared to the general-purpose method using the sand mold.

(Problems to be Solved by the Invention) However, according to the methods using these molded body models, the molded body model must be manufactured with high precision in order to guarantee the clearance between the punch and the die. Its production is extremely troublesome,
There was a problem that design changes could not be easily accommodated.

Furthermore, in Japanese Patent Publication No. 55-6014, a heat-resistant resin sheet is attached to a mother mold such as a wooden mold, this is placed in a casting frame, and a low melting point alloy is poured to cast a female mold. A method is disclosed in which the resin sheet is transferred and adhered to the female mold by the heat generated at this time, and then the casting frame is reversed and a low melting point alloy is poured onto the female mold to cast a male mold. There is. According to this method, mold clearance can be guaranteed with the resin sheet, so the molded body model described above is not required, and various problems associated with the use of the molded body model can be solved.

However, since the above-mentioned heat-resistant resin sheet is a viscous sheet that is thermoset later, when trying to make the single piece closely adhere to the product shape surface of the matrix, not only is local elongation unavoidable, but The occurrence of wrinkles and the entrainment of air become unavoidable.
For this reason, it is necessary to divide the sheet into many small pieces and perform so-called cutting and pasting, which, like pasting sheet wax, requires a great deal of labor and skill, and inevitably reduces work efficiency. Become.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to manufacture a press mold that can easily and accurately obtain a mold without using a molded object model. The purpose is to provide a method.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a heat-resistant mold that has elasticity on the product shape surface of a matrix such as a wooden mold or a resin model, and has a thickness equivalent to the thickness of the product board. The rubber sheet is forcibly brought into close contact with the rubber sheet by suction with negative pressure, and the mother mold is immersed in the molten mold material while maintaining this close contact state.
The mold material is solidified as it is to cast one of the paired molds, and then the mother mold is removed and the heat-resistant rubber sheet is kept in close contact with the one mold. The present invention is characterized in that the mold material is poured directly onto the mold material, and the mold material is solidified as it is to cast the other mold of the pair.

In the present invention, the mold material is not particularly limited as long as it is a low melting point alloy and has low solidification shrinkage; for example, commercially available Bi-Sn
alloy, Bi-Sn-Pb alloy, Bi-Sn-Pb-Sb
You can select alloys, etc., and their melting points are
The temperature is between 50 and 250℃.

Further, in the present invention, the heat-resistant rubber sheet is not particularly limited in its material type as long as it can withstand the melting temperature of the low melting point alloy and maintain its elasticity.
Due to its excellent heat resistance and shape-following properties,
It is desirable to use silicone rubber or fluorine rubber. The thickness of the heat-resistant rubber sheet is such that a mold clearance equivalent to the thickness of the product can be secured between the pair of molds.

In the present invention, the heat-resistant rubber sheet is brought into close contact with the mother mold by negative pressure, but since it is slightly thermally bonded to one mold after casting due to the heat of the molten metal, this is particularly the case. There is no need to consider the adhesion of the rubber sheet to one mold, but
Negative pressure may be used to ensure completeness.

(Function) According to such a method of the present invention, a mold can be easily manufactured by bringing the heat-resistant rubber sheet into close contact with the mother mold or one of the molds without using a molded body model. In addition, the heat-resistant rubber sheet with good elasticity can be evenly and quickly adhered to the product shape surface of the mother mold using negative pressure, which not only improves productivity but also ensures mold clearance. can also be achieved.

(Example) Next, an example of the present invention will be described based on the accompanying drawings.

The present invention is directed to the first step (first step) of casting the die D.
Figure) and the second process of casting the punch P (Figure 2)
It is roughly composed of. In FIGS. 1 and 2, 1 is a die mold tank, which communicates with a reservoir tank 3 via a partition plate 2. In FIGS. The die mold tank 1 and the reservoir tank 3 are covered with a lid plate 5 to maintain a sealed state, and a molten mold material 4 made of a low melting point alloy is held inside them. The lid plate 5 is provided with a large hole 6 corresponding to the die mold tank 1 and a small hole 7 corresponding to the reservoir tank 3. Reference numeral 8 denotes silicone rubber as a heat-resistant rubber sheet, which is stretched over the cover plate 5 so as to cover the hole 6 and is held down by the outer plate 9. Further, a pipe 11 having a pressure gauge 10 in the middle is connected to the hole 7 on the side of the reservoir tank 3, and compressed air is supplied to the pipe 11.

On the other hand, a matrix 12 consisting of a wooden or resin model
and a punch mold tank (negative pressure tank) 21 for storing this mother mold 12 are prepared, and both are placed integrally on the outer plate 9 and can be freely attached to and detached from the die mold tank 1. Fixed. Matrix 12 is
It has an air vent hole 13 that opens on the product-shaped surface 12a and the back surface, and in the fixed state, the product-shaped surface 12a faces into the die mold tank 1 through the silicone rubber 8. Further, the punch mold tank 21 has a hole 22 in its bottom side wall, and a pipe 23 having a vacuum pump 24 in the middle is connected to the hole 22. Note that an air tank 20 with one end closed is submerged in the bottom of the die mold tank 1. The other end of the air tank 20 is connected to the lid plate 5 to communicate with the outside, and a pipe 27 having a vacuum pump 28 in the middle is connected thereto as appropriate (FIG. 2).

In the first step, the mold material 4 is melted and held in the die mold tank 1 in advance, or the mold material 4 that has been separately melted is supplied into the die mold tank 1.
A silicone rubber 8 is placed on top and fixed with an outer plate 9. At this time, the silicone rubber 8 is appropriately stretched. Next, the mother die 12 and the punch mold tank 21 are placed and fixed on the outer plate 9. By this fixing, the product shape surface 12 of the mother die 12
a largely protrudes into the die mold tank 1 while expanding the silicone rubber 8. In this state, next, the vacuum pump 24 in the middle of the pipe 23 is operated to introduce negative pressure into the punch mold tank 21. This negative pressure is supplied between the mother mold 12 and the silicone rubber 8 through the air vent hole 13, and the silicone rubber 8 is brought into close contact with the product-shaped surface 12a of the mother mold 12. At this time, the silicone rubber 8 expands and contracts to make the thickness uniform due to its elastic properties and sticks to the product shape surface 12a, thereby securing the clearance necessary for pressing.

Thereafter, compressed air is supplied into the reservoir tank 3 to push the molten mold material 4 up to the upper end of the die mold tank 1. By this pushing up, the product-shaped surface 12a of the mother die 12 is immersed in the molten mold material 4 via the silicone rubber 8, and the die mold bath 1 is then cooled while maintaining this immersion state. Then, the mold material 4 solidifies,
Die D to which the product shape surface 12a of the mother mold 12 is transferred
(Figure 2) is obtained.

After casting the die D, the second die casts the punch P.
Enter the process. When entering this second step, the negative pressure tank 21 is removed, the mother mold 12 is demolded, the silicone rubber 8 is removed, and then the air vent hole 2 extending from the surface of the die D to the air tank 20 is removed.
Process 5. Next, the silicone rubber 8 is again placed on the die mold tank 1, and the punch mold tank 21 from which the bottom plate has been removed is set on top of the silicon rubber 8, and the vacuum pump 28 in the middle of the pipe 27 is connected as shown in FIG. It is activated to introduce negative pressure into the die mold tank 1. This negative pressure is supplied between the die D and the silicone rubber 8 through the air vent hole 25, and the silicone rubber 8 is brought into close contact with the mold surface of the die D. Thereafter, the punch mold tank 21 with the bottom cover 21a opened is set on the die mold tank 1, and the molten mold material 29 is poured into the punch mold tank 21 in the same manner as described above and solidified as it is to obtain the punch P. It will be done.

Therefore, during each of the above steps, the silicone rubber 8 is interposed between the punch P and the die D.
Thereby, a predetermined mold clearance is secured between the punch P and the die D, and these can be used as they are as a press mold. When used as a press mold, the die mold tank 1 and punch mold tank 21 are set in the press device as they are as holding frames for the die D and punch P, and thereby the die D and punch P are set in the press device. can be simplified. In this embodiment, in particular, the punch mold tank 21 is also used as a negative pressure chamber, so that equipment investment can be reduced.

In the above embodiment, when casting the punch P, negative pressure was used to bring the silicone rubber 8 into close contact with the die D.
is slightly thermally bonded to the die D by the heat of the molten metal 4, and as long as air does not enter between the die D and the obtained die D, the adhesion state is maintained by the action of external pressure (atmospheric pressure). The use of negative pressure can be omitted. In this case, as a matter of course, the work of casting the air tank 20 and the work of providing the air vent hole 25 in the die D become unnecessary.

(Effects of the Invention) As described above in detail, according to the method for manufacturing a press mold according to the present invention, a heat-resistant rubber sheet is used as a base mold or one of the molds without using a molded product model. The mold can be easily manufactured by closely adhering to the mold, and design changes can be easily accommodated. In addition, the heat-resistant rubber sheet with good elasticity can be evenly and quickly adhered to the product shape surface of the mother mold using negative pressure, which not only improves productivity but also ensures mold clearance. can also be achieved. Moreover, since the heat-resistant rubber sheet can be used repeatedly, cost reduction can be achieved by reducing the number of consumables.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the first step of manufacturing a press mold according to the present invention, and FIG. 2 is a cross-sectional view showing the second step. 1...Die mold tank, 4...Mold material, 8...Heat-resistant rubber sheet, 12...Mother mold, 21...Punch mold tank, 24, 28...Vacuum pump, D...Die,
P... Punch.

Claims (1)

[Claims] 1. A heat-resistant rubber sheet having elasticity and a thickness equivalent to the product plate thickness is forcibly applied to the product shape surface of a matrix such as a wooden mold or a resin model by suctioning with negative pressure. The mother mold is immersed in the molten mold material while maintaining this close contact state, and the mold material is solidified to cast one of the paired molds.Then, the mother mold is removed and the mold material is immersed in the molten mold material. While maintaining the heat-resistant rubber sheet in close contact with the product-shaped surface of one mold, the mold material is poured onto the one mold, and the mold material is solidified to form a pair of molds. A method for manufacturing a press mold, characterized in that the other part is cast. 2. The method for manufacturing a press mold according to claim 1, characterized in that silicone rubber or fluorine rubber is used as the heat-resistant rubber sheet. 3. A method for manufacturing a press mold according to claim 1, characterized in that negative pressure is used to bring the heat-resistant rubber sheet into close contact with one of the molds after the mother mold has been removed. .